1. Technical Field
The present invention is directed to an improved method for verification of configuration network parameters in a CDMA network by use of topology analysis. Still more particularly the present invention relates to an improved method for maintaining signal connection when a mobile handset moves across a geographical area by performing topology analysis to sector; neighbor and target lists utilized in CDMA networks.
2. Description of the Related Art
Types of well-known prior art telecommunication systems are Code Division Multiple Access (CDMA) wireless networks. A mobile handset for use by a consumer communicates within the CDMA wireless network when it is located in a geographical region known as a coverage area. The mobile handset moves within the entire area and the network tracks this movement by dividing the coverage area into smaller regions referred to as cells. Cells may either be omni-sector (containing only one sector) or tri-sector (containing three sectors.) A handoff occurs when the mobile handset moves between different sectors in the coverage area. Additionally, the CDMA network internally maintains a database including target and neighbor lists for each sector for use in executing a handoff. These lists are the set of possible sectors into which a mobile handset in a given sector may handoff.
In use, a mobile handset originates in a serving sector. As the mobile handset moves across the geographical region, the serving sector must handoff into a target sector that serves the mobile handset better. There are currently three types of handoffs, namely, softer, soft and hard. The softer handoff is a handoff between two sectors that exist on the same cell wherein both sectors must operate at the same frequency and have common neighbor lists. The soft handoff is a handoff between two sectors that exist on different cells wherein both sectors must operate at the same frequency and the target is in the serving sector neighbor list. The hard handoff is a handoff between two sectors wherein the sectors are not necessarily the same frequency or technology. Hard handoffs are allowed only on certain sector types that triggers a handoff and hands the mobile unit into a sector from the target list (as opposed to the neighbor list).
Soft and softer handoffs are better than hard handoffs because the mobile handset makes the connection with the target sector before breaking with the serving sector. A hard handoff breaks connection with the serving sector before connecting with the target sector. Therefore, a phone call can survive a failed soft or softer handoff attempt than a hard handoff. However, an active phone call may drop if the target sector""s attributes conflict with that of the serving sector. One reason these conflicts arise is when the system administrator does not properly configure the neighbor and target list information for placement in the CDMA database. Incorrect lists lead to failed handoffs causing the line of communication to drop or disconnect.
In view of the above, it should be apparent that a method which provides an automated process for catching many errors that may occur during configuration of neighbor and target lists would be highly desirable. This invention solves this problem in a novel and unique manner not previously known in the art.
It is therefore one object of the present invention to provide an improved method for verification of configuration network parameters in a CDMA network by use of topology analysis.
It is another object of the present invention to provide a method for analyzing an entire CDMA topology by building a directed graph for use in reducing errors that result in dropped calls.
It is yet another object of the present invention to provide an improved method for analyzing neighbor and target lists in a CDMA network for inconsistencies of frequency, band class and pilot value.
The foregoing objects are achieved as is now described. A method for analyzing the topology of a CDMA network with respect to both neighbor and target lists is disclosed. The method first defines a language that creates an input source file for communicating the layout of the CDMA network. The language expresses the sector-neighbor list relationships of all sectors in the CDMA network. Next, the method parses and builds a directed graph from the input source file to perform topology analysis of the CDMA network. The method then analyzes the input source file and directed graph for possible errors in the network layout that will lead to dropped calls. The method renders a report to the user about those error conditions and emits a file to be used as input into the CDMA network database.